Screening of Heterogeneous Photocatalysts for Water Splitting

In this contribution, a simple method for the screening of photocatalytic activity of catalyst materials is presented. The method is based on two steps the immobilization of the photocatalyst and the subsequent testing of their photocatalytic activity, using the gas evolution at the solid liquid interface. Up to four catalysts can be tested under the same conditions. The observed gas evolution for selected photocatalysts is consistent with trends reported in the literature from conventional photocatalytic reactor

Highly Active TiO2 Photocatalysts for Hydrogen Production through a Combination of Commercial TiO2 Material Selection and Platinum Co-Catalyst Deposition Using a Colloidal Approach with Green Reductants

In this contribution, four different commercial TiO2 catalysts (P25, P90, PC105, and PC500) were screened for the photocatalytic production of hydrogen using ethanol as the sacrificial agent. The physico-chemical properties of the TiO2 powders were characterized by using different methods. The photocatalysts mainly vary in the ratio of anatase and rutile phases, and in the surface area. It was found that the photocatalytic activity is governed by the surface area of the photocatalyst. Pure TiO2,PC500 showed the best performance, and in comparison to P25, the activity was more than twenty times higher due to its high surface area of about 270 m2 g−1. For further improvement of the photocatalytic activity, platinum nanoparticles (PtNPs) were immobilized onto TiO2,PC500 using two methods: a colloidal approach and a photodeposition method. For the reduction of the platinum salt precursor in the colloidal approach, different green reducing agents were used in comparison to ascorbic acid. The obtained platinum nanoparticles using natural reductants showed a higher photocatalytic activity due to the formation of smaller nanoparticles, as proven by transmission electron microscopy (TEM). The highest activity was obtained when mangosteen was used as the green reducing agent. Compared to ascorbic acid as a classical reducing agent, the photocatalytic activity of the Pt@TiO2,PC500 prepared with mangosteen was about 2–3 times higher in comparison to other as-prepared photocatalysts. The Pt@TiO2,PC500 catalyst was further studied under different operating conditions, such as catalyst and sacrificial agent concentration

Highly Active TiO2 Photocatalysts for Hydrogen Production through a Combination of Commercial TiO2 Material Selection and Platinum Co-Catalyst Deposition Using a Colloidal Approach with Green Reductants

In this contribution, four different commercial TiO2 catalysts (P25, P90, PC105, and PC500) were screened for the photocatalytic production of hydrogen using ethanol as the sacrificial agent. The physico-chemical properties of the TiO2 powders were characterized by using different methods. The photocatalysts mainly vary in the ratio of anatase and rutile phases, and in the surface area. It was found that the photocatalytic activity is governed by the surface area of the photocatalyst. Pure TiO2,PC500 showed the best performance, and in comparison to P25, the activity was more than twenty times higher due to its high surface area of about 270 m2 g−1. For further improvement of the photocatalytic activity, platinum nanoparticles (PtNPs) were immobilized onto TiO2,PC500 using two methods: a colloidal approach and a photodeposition method. For the reduction of the platinum salt precursor in the colloidal approach, different green reducing agents were used in comparison to ascorbic acid. The obtained platinum nanoparticles using natural reductants showed a higher photocatalytic activity due to the formation of smaller nanoparticles, as proven by transmission electron microscopy (TEM). The highest activity was obtained when mangosteen was used as the green reducing agent. Compared to ascorbic acid as a classical reducing agent, the photocatalytic activity of the Pt@TiO2,PC500 prepared with mangosteen was about 2–3 times higher in comparison to other as-prepared photocatalysts. The Pt@TiO2,PC500 catalyst was further studied under different operating conditions, such as catalyst and sacrificial agent concentration.DFG, 390540038, EXC 2008: Unifying Systems in Catalysis "UniSysCat

Polyoxometalate POM boosting the light harvesting ability of graphitic carbon nitride for efficient photocatalytic hydrogen production

Phosphomolybdic acid PMA was used to achieve simultaneously P doping and heterojunction construction of graphitic carbon nitride gCN . P gCN PMAx composites were obtained via post thermal annealing of bulk gCN PMAx and characterized in detail using different techniques including XRD, XPS, SEM, and DRS. As an in situ hard templating agent and doping source, the loaded PMA helps to provide porous structured materials and reinforced electronic properties whereby many transitions are enhanced resulting in the improvement of light harvesting. The electronic properties of gCN are improved strongly with the increased amount of PMA loaded, but the crystallinity becomes worse and the material becomes much more amorphous and disordered. The materials were investigated for the hydrogen evolution reaction HER showing the highest H2 evolution performance of 625 amp; 956;mol g amp; 8722;1 h amp; 8722;1 for the P gCN PMA1.5 sample, which is almost 4 times higher than that of gCN with 167 amp; 956;mol g amp; 8722;1 h amp; 8722;1. The P gCN PMA1.5 sample was investigated under long term irradiation and in recycling tests indicating the good photocatalytic stability of this material. The apparent quantum efficiency AQE exhibited by P gCN PMA1.5 0.7 is 7 times higher than the AQE measured exhibited by gCN. This is evidence of the boosting effect exhibited by the loading of PMA onto the surface of gCN 0.1 . Thus, this study aims to offer a novel strategy to improve the activity of gCN by applying polyoxometalates as modifiers for better light harvestin